Cysteineglucuronolactone and salts thereof are described in Laid-Open Japanese Patent Application Kokai Nos. 56-166189 and 57-175197, respectively, but as regards their effects, only the effect of cysteine and that of glucuronolactone are anticipated.
There has also been disclosed a method for producing cysteineglucuronic acid or sodium cysteineglucuronate which comprises reacting cysteine with glucuronic acid or sodium gluconate but as to the application of such compounds it has been merely described that they are expected to be of use as, for example, hapatotonics and therapeutic agents for radiation disorder (Japanese Patent Publication No. 37-16735).
Further, as a compound having the actions of cysteine, glucuronic acid and calcium in one compound and having the instability of cysteine overcome, calcium cysteineglucuronate as well as a method for production thereof has been disclosed but no reference has been made to its uses except those mentioned hereinabove (Laid-Open Japanese Patent Application Kokai No. 56-150075).
An anticataract drug comprising a salt of cysteineglucuronic acid has also been disclosed (Laid-Open Japanese Patent Application Kokai No. 57-18615).
As has been mentioned just above, Japanese Patent Publication No. 37-16735 does not disclose any information on the application of cysteineglucuronic acid other than the possible uses referred to above. Any use invention in the pharmaceutical field comes to be established only after its relevant utility has been sufficiently demonstrated and verified by a series of biological experiments and tests and the description in the above-mentioned patent literature cannot be said to teach pharmaceutical uses in the genuine sense of the term.
Therefore, one must conclude that the effects of cysteineglucuronolactone, cysteineglucuronic acid and their respective salts on the liver, for example, the effects of such compounds on acute or chronic hepatitis and hepatocirrhosis, have not been elucidated as yet.
The present invention has resolved the question and provides new uses for the above-mentioned compounds.